1. Field of the Invention
The present invention relates to a correction circuit correcting a current pulse waveform to be applied to a surface-emitting semiconductor laser which emits laser light from an upper surface as well as a drive circuit and a light emitting drive including the correction circuit. The invention also relates to a correction method of the current pulse waveform applied to the semiconductor laser.
2. Description of the Related Art
The surface-emitting semiconductor laser is different from a Fabry-Perot resonator semiconductor laser in related art, which emits light in a direction orthogonal to a substrate and in which many resonator structures can be arranged on the same substrate in a two-dimensional array state. Accordingly, the surface-emitting semiconductor laser attracts attention in technical fields of data communication, printers and the like.
The surface-emitting semiconductor laser generally includes a Mesa-shaped resonator structure in which a lower DBR layer, a lower spacer layer, an active layer, an upper spacer layer, a current confinement layer, an upper DBR layer and a contact layer are stacked in this order. In such semiconductor laser, an oscillation wavelength is determined by an effective resonator length of the resonator structure, and the magnitude of light output will be largest in a emission wavelength corresponding to a bandgap of the active layer. Accordingly, the resonator structure and the active layer are normally configured so that the effective resonator length of the resonator structure and the emission wavelength of the active layer are equal to each other (refer to JP-2008-306118 (Patent Document 1)).